Regular-expression Learning

1. Common meta characters

.	Match any character other than line break
\w	Match letters or numbers or underscores or kanji
\s	Match any of the whitespace characters
\d	Match numbers
\b	Match the beginning or end of a word
^	Match the start of a string
$	Match the end of a string

2. Character escapes

Such as. , * must use \. and \*. To find \ itself, you also have to use \ \.

3. Repeat

*	Repeat 0 or more times
+	Repeat one or more times
?	Repeat 0 or one time
N	Repeat n times
{N,}	Repeat N or more times
{N,m}	Repeat N to M times

[All-in-one] indicates that one

4. Branch Matching

The specific method is to separate the different rules with a |

0\d{2}-\d{8}|0\d{3}-\d{7} This expression can match two phone numbers separated by a hyphen: a three-bit area code, a 8-bit local number (such as 010-12345678), a 4-bit area code, and a 7-bit local number (0376-2233445).

5. Grouping is about to be () as a group

mentioned earlier how to repeat a single character (directly after the character with a qualifier); Repeat multiple characters with parentheses to specify the sub-expression (also called grouping), then you can specify the number of repetitions of the subexpression, and you can do some other actions on the subexpression (described later).

(\d{1,3}\.) {3}\d{1,3} is a simple IP-address matching expression. To understand this expression, parse it in the following order:\d{1,3} matches numbers from 1 to 3 digits,(\d{1,3}\.) {3} matches three digits plus an English period (this whole is the grouping) repeats 3 times, and finally adds one to three digits (\d{1,3}).

Http://tool.oschina.net/regex regular Match Test

Regular-expression Learning